1. Field of the Invention
The field of the invention relates to locking devices and methods, more particularly the field of the invention relates to protecting against the theft of heavy construction equipment, mobile farm equipment and the like.
2. Brief Description of the Prior Art
A wide variety of mobile apparatus is used in the construction and farming industries. Such equipment is used in the moving and removing of earth, in the lifting and transporting of heavy materials, etc. The appararatus normally incorporates hydraulic cylinders which are power operated to move between positions of various extension, causing the tool equipment and the apparatus to perform its work functions. Hydraulic cylinders are also used to position temporary supports which improve the stability of the equipment during work operations.
It has been recognized that hydraulic cylinders can be immobilized by placing safety devices along the shaft of the cylinder. U.S. Pat. No. 3,135,555 to MeCaskey discloses a safety guard for the ram of an hydraulic hoist. In this patent there is disclosed the use of the safety guard to maintain the bed of a dump truck in a raised position. Similarly, U.S. Pat. No. 2,397,516 discloses a safety locking device that is adapted to lock a piston rod in a position to prevent accidental closure of bomb bay doors on workmen. U.S. Pat. No. 4,122,758 discloses a U-shaped support member to straddle the rod of a lift cylinder of a loader-type vehicle. Another such device for use with the brake assembly of railroad cars is disclosed in U.S. Pat. No. 3,430,735. Devices of this type serve their safety function quite well, but they do not serve the function of preventing theft, since they are readily removable. Moreover, many of the examples of use would not significantly affect the theft of the vehicle they are used on.
Theft of such mobile equipment is a problem of major proportions. Because of the equipment's inherent mobility, it is very susceptible to theft. When left unattended, the vehicle can easily be jump started and driven away. Even when attended, the vehicles are often not substantially protected against theft. Various pieces of equipment are often spread out over large areas. As a result, security is often inadequate to protect against unauthorized trespass. It is not unusual for a vehicle to be driven away (or onto a trailer) before the unauthorized trespass is detected.